1. Field of the Invention
The invention relates generally to the field of photography, and in particular to a photographic camera having an electronic flash unit capable of changing its extension from the camera body and its illumination angle in accordance with a change in the focal length of the taking lens.
2. Description of the Prior Art
A current trend in most camera design is to incorporate an electronic flash unit in the camera body and yet make the camera body relatively small in order to improve its ease of storage, portability and handling. As a consequence of making the camera body small, however, the separation between the built-in flash unit and the taking lens is reduced, which possibly creates an undesirable effect commonly known as "red-eye". When a flash unit is used with color print film to take pictures, red-eye is typified by the pupils in the eyes of a person being photographed coming out red-tinted on a color print made from the negative. This phenomenon is attributable to the incidence into the taking lens of the red light reflected from the retinas in the person's eyes illuminated by the flash light.
As is known, red-eye may be substantially prevented by increasing the separation between the flash unit and the taking lens. For example, U.S. Pat. No. 4,978,989, issued Dec. 18, 1990, suggests popping up the flash unit from a lower position relative to the camera body to a higher position relative to the camera body in accordance with an increase in the distance between a person to be photographed and the taking lens. Presumably, then, the light emitted from the flash unit will reach the eyes of a person being photographed at too great an angle to be reflected by his or her retinas into the taking lens.
Alternatively, red-eye may be substantially prevented by changing the separation between the flash lens and the light-emitting means, i.e. the flash tube and/or the flash reflector, of the flash unit to change the illumination angle of the flash unit in response to a change in the focal length of the taking lens. For example, U.S. Pat. No. 4,847,647, issued Jul. 11, 1989, suggests first flipping up the flash unit from an inoperative storage position folded against the camera body to an operative erect position elevated above the camera body and then increasing the separation between the flash lens and the light-emitting means of the flash unit to decrease the illumination angle of the flash unit as the focal length of a zoom lens is changed from a shorter one, e.g. 35 mm, to a longer one, e.g. 70 mm.